分子进化与基因组多样性（张亚平）知识库

测定了金色果蝇复合种(Drosophila auraria species complex)5个姐妹种(sibling species)和D.rufa的period(per)基因的Thr-Gly区段序列.该区段序列分析表明:DNA序列的碱基组成拥有果蝇其他基因的共同特点;颠换数多于转换数,两两物种间的颠换率与转换率的总比值为2～5,密码子第3位的颠换与转换的比值为2.5～5;同义替换/异义替换(Ks/Ka)值远大于10,且有的物种间根本不存在非同义突变,低的Ka值说明该复合种的per基因Thr-Gly区段在进化过程中可能承受着较强的选择压力.运用所得的核苷酸序列构建Drosophila auraria复合种的系统发育树,为澄清该类群的系统演化关系提供了新的线索.

The Thr-Gly regions of the period gene were sequenced in the five sibling species of the Drosophila auraria species complex and D.rufa.Base composition of the species complex is coherent to that of the other gene in Drosophila.The transversions are more than the transitions;the total rate of transversion to transition is 2 to 5 between pairwise species,and the rate of transversion to transition in the third codon is 2.5 to 5.The rate of synonymous (Ks) to non-synonymous (Ka) is far higher than 10.The insynonymous mutation does not exist between some species,the low Ka value indicats that the The-Gly regions in the period gene of Drosophila auraria species complex have undergone selection pressure in their evolution.The phylogenetic tree from DNA sequences of Thr-Gly regions is important to clarify the phylogenetic relationships of the species complex.